What is the oldest method of printing in art?

In China seals were used since at least the Shang dynasty. In the Western Zhou, sets of seal stamps were encased in blocks of type and used on clay moulds for casting bronzes. By the end of the 3rd century BC seals were also used for printing on pottery. In the Northern dynasties textual sources contain references to wooden seals with up to 120 characters.

Also, Stone and bronze blocks

Woodblock printing (200 AD)

Legendary origins

Lithography

Lithography

etc.